12 Oct 2021

Higher BMI increases risk of developing common cancers

Being overweight and obese puts people at greater risk of developing 10 of the most common cancers, according to research in the Lancet medical journal.

Higher body mass index (BMI) increases the risk of developing 10 of the most common cancers.

Each 5 kg/m increase in BMI was clearly linked with higher risk of cancers of the uterus (62%), gallbladder (31%), kidney (25%), cervix (10%), thyroid (9%), and leukemia (9%). Higher BMI also increased the overall risk of liver (19%), colon (10%), ovarian (9%), and breast cancers (5%), but the effects on these cancers varied by underlying BMI and by individual-level factors such as sex and menopausal status.

Even within normal BMI ranges, higher BMI was associated with increased risk of some cancers

The way that fat is distributed around the body can also affect the risk of cancer. Apple-shaped people who put on weight around their stomach may have higher risks than pear-shaped people who put on weight around their hips.

Keeping a healthy weight reduces cancer risk and losing weight may reduce cancer risk

One study found that women who lost 20 pounds or more had 11% lower risks of cancer overall compared to women who had never lost that much weight. 49 Another study found that women who lost 10kg since menopause and kept the weight off more than halved their risk of breast cancer.

When people try lose weight through short-term fixes, in most cases, the end up putting the weight back on. Its unclear how this weight cycling affects the risk of cancer. But at least one study found that women whose weight had gone up and down by over 10 pounds, more than ten times, had higher risks of kidney cancer than those whose weight was stable. 36 While this was just a single study, it does suggest that the best way to reduce the risk of cancer is to maintain a healthy bodyweight over time.

Parents can reduce their childrens cancer risk in adult life by encouraging them to eat healthily and keep active

Eating habits established in childhood often endure after many years. In 1993, a group of scientists showed that at least half of obese children were still obese as adults 50. And this proportion is likely to be even higher now.